Thursday, March 9, 2017

Scientists in Eureka answer student questions:

Out for a walk in Eureka!
The ACE/OSIRIS sunrise campaign is run by a team of scientists who are currently in Eureka, Nunavut to study changes in the Arctic atmosphere. After learning about studying the atmosphere in Eureka, students at Joamie Elementary had some great questions for the scientists about climate change, the atmosphere, temperature, and the northern lights. Here are their responses:

Question from Maria Rose: How do you think Climate Change will affect Canada?
Answer by: Paul Jeffery

You might think climate change can be summed up simply by saying that the average temperature will increase. It doesn't sound too bad when put like that, and if you live in a colder place the sound of a warmer climate might even be pleasant. But increased temperatures is just one of a whole host of impacts climate change can have upon Canada and the world at large. With climate change we can expect changes in precipitation, increasing it in some regions leading to floods or decreasing in others leading to droughts and more forest fires. Canada is a nation defined by its forests and winding river ways and this facet of our identity is under threat. Additionally melting glaciers and sea ice lead will lead to coastal flooding (8 of Canada's provinces and all 3 territories will be impacted by this) and the loss of habitat for numerous animal species such as polar bears. Finally due to temperature changes insect populations will likely rise leading to an increase in insect-carried diseases and the destruction of crops by pests, harming Canadians and their livelihood directly. This is why we as Canadians must try our hardest to work against climate change, to make a better future for us all and avoid this destructive fate. 

Question from
Lily Rose McIntyre: What is the highest number you've gotten on the pyranometer?
Answer by: Kristof Bognar
Sunrise in Eureka (Photo by Ghazal)
Unfortunately I don't have access to pyranometer data now, but I'm working on it. In any case, the highest numbers would not be recorded this time of the year. The pyranometer measures the amount of sunlight hitting the ground, and so the higher the sun is in the sky, the higher the measured value. In Eureka, the sun is barely above the horizon in the spring, and so we measure values that you get during sunrise or sunset down south. The highest numbers would be measured during the summer solstice, when the sun is at its highest point in the entire year. In Eureka, that's around 33 degrees above the horizon. This means that the maximum value we can measure on the pyranometer is little above half of the maximum possible value (that you measure when the sun is directly overhead). The actual maximum value in Eureka would be 5-600 W/m^2. To sum it up, the higher north you go, the lower the maximum measured values get, simply because the sun is so low in the sky.

Question: Why is the atmosphere see-through?
Answer by: Emily McCullough

The atmosphere is see through... but only for some colours! 

For the atmosphere to be see-through, light has to be able to pass through it without too much happening to interrupt it on the way. Or at least anything that happens to the light needs to make it look like nothing happened to it. If it changes colour, or changes direction, or disappears entirely, when it hits the stuff, then the stuff it went through is not transparent.

The atmosphere is made of gas. It's got oxygen molecules, nitrogen molecules, water vapour, ozone, lots of things. There's quite a lot of space between all those air molecules, so sometimes when light tries to get through, it doesn't actually hit anything on its way, and the atmosphere can be transparent because of this.

Sometimes instead, the molecules absorb the light, and then send out some light the same colour, in the same direction the original light was going. This is just as good as if the light never hit anything, because we can't tell the difference just by looking. The atmosphere looks see-though because of this, too.

The atmosphere isn't always transparent to all colours. Ozone and water vapour can absorb UV light, so the atmosphere is not totally transparent to UV colours. Nitrogen can send blue light off in all sorts of directions (but not so much with red light), so the atmosphere is not quite as transparent for blue light as it is for red light.

Question: Why is it so cold up North but in some places it's warm all the time?
Answer by: Ghazal Farhani
The polar regions don't receive a lot of sunlight, and that's the reason they are so cold. In winter time the sun is not coming above the horizon, and the poles are experiencing continuous night time. Even during the summer, the sun is not really high above the horizon and that's the reason the summer is cool at the poles as well. In the tropical regions, the sun always rises high above the horizon, and can heat up the surface easily. Moreover, because Earth is spherical, the sunlight has to travel longer distances through the atmosphere to reach the poles, while the distance for the light travelling through the atmosphere to reach to the tropical regions is shorter. This means that more of the sunlight gets to the surface in the tropical regions than in the poles, and therefore the tropical regions are heated more.


Question: Why are the Northern Lights Green?
Answer by: Gurpreet Singh
Earth's atmosphere is mainly composed of nitrogen and oxygen gas. The topmost regions of the atmosphere are constantly bombarded by particles from the sun, and when these particles hit the nitrogen and oxygen molecules, a lot of energy is deposited. When molecules have more energy than normal, they are in an 'excited state'. These excited gas molecules come back to their normal state by releasing the surplus energy in the form of light. This light is generally referred to as "Northern lights" or "auroras". The color of northern lights depend on the gas being excited. If oxygen gas molecules are exchanging the energy then the lights appear to be greenish-yellow, and if it is the nitrogen gas molecules, lights are blue in color. 
Cool fact: Auroras also occur near the Earth's magnetic South Pole!


Question: How does the temperature change?

Answer by: Kristof Bognar
Keeping the instruments warm at -40!
In the springtime, temperatures in Eureka hover around -30, -40 degrees Celsius. It has been particularly cold while we've been up here, sometimes down to -48. With the wind, that really bites. The exact temperature depends on the weather: winds might bring cold air from above the sea ice, or a larger storm might bring warmer air from below the Arctic circle. The more interesting things happen locally, however. Most of us work in a lab that's sitting on a 600m hill, and it is often 10-15 degrees warmer up there than down at the weather station. In most parts of the world, the temperature would decrease as you go up, but here the surface is often the coldest. Since there is little sunlight to warm up the ground, it cools down faster than the air above it, and this creates a temperature 'inversion' so that it's warmer as you go up. Sometimes this inversion disappears, and that's when we get the really cold days up in the lab -- and working outside is a lot less fun in -45 than in -30. Either way, you can actually learn a lot about the state of the atmosphere just by having two thermometers, one at sea level, and one higher up on a hill.

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